Apparatus with first and second close points on media-facing surface of magnetic head

ABSTRACT

A magnetic head includes a read transducer and a write transducer at a media-facing surface of the magnetic head. The magnetic head includes at least one heater that causes heat deformation at the media-facing surface in response to different first and second energizing currents. The first energizing current results in a first close point between the media-facing surface and a recording medium. The second energizing current results in a second close point between the media-facing surface and the recording medium. The second close point is at a different location in the media-facing surface than the first close point.

RELATED PATENT DOCUMENTS

This application is a divisional of U.S. Ser. No. 14/206,657, filed Mar.12, 2014, to which priority is claimed and which is hereby incorporatedby reference in its entirety.

BACKGROUND

A heat-assisted, magnetic recording (HAMR) data storage medium uses ahigh magnetic coercivity material that is able to resistsuperparamagnetic effects (e.g., thermally-induced, random, changes inmagnetic orientations) that currently limit the areal data density ofconventional hard drive media. In a HAMR device, a small portion, or“hot spot,” of the magnetic medium is locally heated to its Curietemperature, thereby allowing magnetic orientation of the medium to bechanged at the hot spot while being written to by a write transducer(e.g., magnetic write pole). After the heat is removed, the region willmaintain its magnetic state due to the high coercivity of medium,thereby reliably storing the data for later retrieval.

SUMMARY

The present disclosure is related to apparatus with first and secondclose points on a media-facing surface of a magnetic head. In oneembodiment, an apparatus includes A magnetic head includes a readtransducer and a write transducer at a media-facing surface of themagnetic head. The magnetic head includes at least one heater thatcauses heat deformation at the media-facing surface in response todifferent first and second energizing currents. The first energizingcurrent results in a first close point between the media-facing surfaceand a recording medium. The second energizing current results in asecond close point between the media-facing surface and the recordingmedium. The second close point is at a different location in themedia-facing surface than the first close point.

In another embodiment, a method involves applying a first energizingcurrent to a heater of a magnetic head responsive to entering a firstoperational mode of the magnetic head. The first energizing currentresults in a first close point between the magnetic head and a recordingmedium. The method further involves applying a different, secondenergizing current to the heater responsive to entering a secondoperational mode of the magnetic head. The second energizing currentresults in a second close point between the magnetic head and therecording medium. The second close point is at a different location on amedia-facing surface of the magnetic head than the first close point.

In another embodiment, a magnetic head includes a read transducer at amedia-facing surface of the magnetic head and a write transducer at themedia-facing surface and located in a downtrack direction relative tothe read transducer. A contact pad is disposed at the media-facingsurface between the read transducer and the write transducer. Themagnetic head includes at least one heater that causes heat deformationat the media-facing surface in response to different first and secondenergizing currents. The first energizing current results in a firstclose point between the media-facing surface and a recording medium tobe proximate the read transducer. The second energizing current resultsin a second close point between the media-facing surface and therecording medium to be proximate the contact pad.

These and other features and aspects of various embodiments may beunderstood in view of the following detailed discussion and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following diagrams, the same reference numbers may be used toidentify similar/same/analogous components in multiple figures. Thefigures are not necessarily to scale.

FIG. 1 is a perspective view of a slider assembly according to anexample embodiment;

FIG. 2 is a cross-sectional view illustrating portions of a slider bodynear a plasmonic transducer according to an example embodiment;

FIGS. 3 and 4 are cross-sectional views of the slider body of FIG. 2showing different protrusions according to example embodiments;

FIG. 5 is a block diagram showing a system according to an exampleembodiment; and

FIG. 6 is a flowchart showing a method according to an exampleembodiment.

DETAILED DESCRIPTION

The present disclosure is generally related to an apparatus (e.g., aHAMR read/write head) having multiple controllable protrusion regions ata surface of the apparatus (e.g., air bearing surface) that faces arecording media. These protrusion regions, also referred to as closepoints, can be selectably enabled to cause different regions of themedia-facing surface to protrude during different operating modes. Forexample, different close points may be activated during respective readand write operations of the apparatus. While embodiments described belowinclude HAMR read/write heads, it will be understood that these conceptsmay be applicable to other devices, including non-HAMR read/write heads.

In reference to FIG. 1, a perspective view shows HAMR slider assembly100 according to an example embodiment. The slider assembly 100 includesa laser diode 102 located on input surface 103 of a slider body 101. Inthis example, the input surface 103 is a top surface, which is locatedopposite to a media-facing surface 108 that is positioned over a surfaceof a recording media (not shown) during device operation. Themedia-facing surface 108 faces and is held proximate to the moving mediawhile reading and writing to the media. The media-facing surface 108 maybe configured as an air-bearing surface (ABS) that maintains separationfrom the moving media surface via a thin layer of air.

The laser diode 102 delivers light to a region proximate a HAMRread/write head 106, which is located near the media-facing surface 108.The energy is used to heat the recording media as it passes by theread/write head 106. Optical coupling components, such as a waveguide110, are formed integrally within the slider body 101 (near a trailingedge surface 104 in this example) and function as an optical path thatdelivers energy from the laser diode 102 to the recording media via aplasmonic transducer 112. The plasmonic transducer 112 is near theread/write head 106 and causes heating of the media during recordingoperations. It will be understood the illustrated arrangement ofcomponents (e.g., top-mounted laser) is provided for purposes ofillustration and not limitation, and the concepts below may beapplicable to a variety of HAMR and non-HAMR read/write heads.

In FIG. 2, a cross-sectional view illustrates portions of the sliderbody 101 near the media-facing surface 108 according to an exampleembodiment. The plasmonic transducer 112 is shown proximate to a surfaceof magnetic recording medium 202, e.g., a magnetic disk. The waveguide110 delivers electromagnetic energy to the plasmonic transducer 112,which directs the energy to create a small hotspot 208 on the medium202. A magnetic write pole 206 causes changes in magnetic flux near themedia-facing surface 108 in response to an applied current. Flux fromthe write pole 206 changes a magnetic orientation of the hotspot 208 asit moves past the write pole 206 in the downtrack direction(z-direction).

The magnetic write pole 206 is part of a larger write transducer 207,which also includes return poles 211, 209 and coils 210. The writetransducer 207 is located downtrack (z-direction in this example)relative to a read transducer 212. The write transducer 207 need not bealigned with the read transducer 212 in a crosstrack direction. The readtransducer 212 may include at least a read sensor, e.g., giantmagnetoresistive (GMR) stack, tunneling magnetoresistive (TMR) stack,and the like. The read transducer 212 may also include magnetic shieldsto reduce interference.

Generally, the read transducer 212 and write transducer 207 are keptseparated by the medium 202 by a gap (e.g., air gap) during operation.The read transducer 212 and write transducer 207 are designed to operatewithin a defined separation distance range from the medium 202, and theair gap alone may not control this separation with the desiredprecision. As such, an additional clearance mechanism is used to finelyadjust clearance between transducers 212, 207 and the medium 202.

In this example, one or more heaters 214, 216 are used to activelyadjust clearance between transducers 212, 207 and the medium 202.Although two heaters 214, 216 are shown, the embodiments described belowmay use just one heater at one of the illustrated locations, orelsewhere in the slider body. By applying current to the heaters 214,216, localized heating of the surrounding material will cause aprotrusion at the media-facing surface 108, as indicated by dashed line218. This protrusion 218 is also referred to as a “close point,” in thatit is the closest point between the medium 202 and the slider body 101.There may be more than one close point, in which case a “close point”may refer to the closest point to the medium in a specific region, eventhough there may be other points with smaller clearances elsewhere alongthe media-facing surface 108.

Changing the close point by the application of current to one or more ofthe heaters 214, 216 allows selectably adjusting the amount and/or shapeof the protrusion 218. In this way, the heaters 214, 216 can be used tocontrol respective clearances between the transducers 212, 207 and themedium 202 during read/write modes. As will be described in greaterdetail below, application of different first and second currents to atleast of the heaters 214 also facilitates changing a location of theprotrusion 218, thus causing different close points to occur duringdifferent operational modes.

Other components near the media-facing surface 108 may also contributeto protrusion, e.g., influence a location and/or magnitude of theprotrusion. For example, the waveguide 110 and NFT 112 can exhibitsignificant local temperature increases during operation due toabsorption of optical energy, thereby increasing protrusion near the NFT112. The write transducer 207 may also cause a local temperatureincrease due to resistive and inductive heating caused by the coils 210.Generally, these sources of heat may be relatively predetermined atleast during recording due to the need to deliver a particular level ofoptical energy and magnetic flux to the medium 202. However, somevariation may be possible, and other components, such as one or moreheaters, may be subject to a varying current that allows fine adjustmentof the write-mode clearance.

In order to measure the clearance between the transducers 212, 207 andthe medium 202, a controller (not shown) may measure temperatures nearthe media-facing surface via a temperature sensor 220. The temperaturesensor 220 may detect contact and/or proximity between the transducers212, 207 and the medium 202 by measuring a local temperature. Thetemperature sensor 220 may have a temperature coefficient of resistancethat causes a predictable change in resistance across the sensorresponsive to changes in local temperature. The temperature sensor 220may detect contact and clearance by measuring a change in temperatureprofile according to a known pattern (e.g., sudden drop in temperaturedue to initial contact with the medium 202).

Although the slider body 101 is designed to minimize contact between themedia-facing surface 108 and the recording medium 202 during operation,some contact may inevitably occur during device operation. Themedia-facing surface 108 and recoding medium 202 include surfacecoatings (e.g., diamond-like carbon) to minimize damage due to suchimpacts. However, if the coating wears away, some components may causeproblems if exposed at the media-facing surface. For example, the NFT112 may be made of gold or some other metal (e.g., silver, aluminum,copper) that causes contamination of the medium 202 and/or media-facingsurface 108 if allowed to contact the medium. In another example, thewrite pole 206 may be configured to be the closest point to the medium202 during write operations. If the coating wears away from the writepole 206, the exposed material (which includes iron) may becomecorroded.

In the illustrated embodiment, a contact block 222 is included downtrackbetween the read transducer 212 and the write transducer 207. Thecontact block 222 is made of a hard, corrosion-resistant material, andmay be exposed or covered, e.g., by a coating, such as diamond-likecarbon (DLC). The contact block 222 could be formed from patternedovercoat or could be deposited during wafer-level fabrication.

The contact block 222 may include at least a thin layer 222 a near thesurface. It may include a relatively thick element, push block 222 b,deposited on the wafer, extending into the recording head. A portion ofthe thin film 222 a extends along the push block 222 b away from themedia-facing surface. If formed at the wafer level, the thin film 222 acould be made by first plating a large block of material that forms thepush block 222 b a fraction of a micron away from the media-facingsurface 108, and then coating this block of material with the thin film222 a, such that the film coats the side of the push block 222 b.

After dicing and lapping, the thin coated film 222 a forms a sheet ofmaterial on the media-facing surface 108. The thin film 222 a which isexposed at the media-facing surface 108 and the push block 222 b may bechosen from materials known to protrude more than the write pole 206 orshields of the read transducer 212. Making the contact block 222 out ofa high-protrusion (mechanically hard) material such as Ta or Ru reducesthe some thermo-mechanical design constraints. Other materials for thecontact block 222 include nonmagnetic metals and dielectrics. The thinfilm 222 a portions exposed at the media-facing surface 108 should besuitable for exposure in a corrosion-sensitive environment. The size ofthe contact block 222 would be chosen in conjunction with the heatershape to provide the desired level of actuation and area of contact.

The use of the contact block 222 facilitates selectably changing a closepoint region by using different currents energizing the one or moreheaters 214, 216. An example of how different close points may beobtained is shown in the block diagrams of FIGS. 3 and 4. In FIG. 3, theblock diagram shows an exaggerated protrusion profile used during readoperations of a magnetic head (also referred to herein as a read mode).Heater 216 is activated via a first current such that close point 302protrudes from the media-facing surface 108. Close point 302 is at ornear the read transducer 212, which can minimize clearance of the readtransducer 212 during read operations.

In FIG. 4, the block diagram shows an exaggerated protrusion profileused during write operations of a magnetic head (also referred to hereinas a write mode). Heater 216 is activated via a different second currentsuch that close point 402 protrudes from the media-facing surface 108.Close point 402 is at or near the contact block 222. This minimizes thechances that the NFT 112 and/or write pole 206 contacts the recordingmedium during write operations. The contributions of the NFT 112 andwrite transducer 207 to local heating at the media-facing surface 108can help shift the close point 402 towards the contact pad 222 duringwrite operations compared with the close point 302 seen during readingin FIG. 3.

The thermo-mechanical design of the slider body 101 is configured suchthat when write mode is energized, the close point moves from the readerto the adjacent, downtrack central contact block 222. This may beenabled by positioning the heater 216 sufficiently far uptrack toactuate the reader and contact block portions of the head (yielding lowgamma), and relying on the write coils 210 or laser heating to protrudethe writer section. It could also be enabled by using more than oneheater to control the contact point location. The elevation from themedia-facing surface 108 of the writer 207 relative to the contact block222 is selected to maintain sufficient writer clearance to prevent wear,while positioning the write pole 206 low enough to write. Thisdifference in elevation may be as little as a few nanometers.

By positioning the contact pad immediately downtrack of the readersection, the design produces only a small change in contact pointlocation when changing operating modes. This assists with the functionof a clearance or contact-detection device such as a sensor, whichdepends on proximity to the contact location and the frictional heatingcaused by contact. In one implementation, a single temperature sensormay be used, positioned between the reader top shield and the uptrackside of the contact pad. This location facilitates minimizing changes inclearance between the temperature sensor and the recording medium whenthe first and second energizing currents are applied resulting in firstand second close points.

While the illustrated close point 302 in FIG. 3 is shown at the readtransducer 212, it will be understood that the close point 302 mayinstead be closer to the contact block 222. For example, the contactblock 222 may be elongated along the downtrack direction, so that thefirst close point 302 corresponds to an end of the contact block 222near the read transducer 212, and the second close point 402 correspondsto another end of the contact block 222 near the write transducer 207.In such a case, one of the respective read and write transducers 212,207 may be closer to the media surface than the other during differentoperational modes, yet in either mode the contact block 222 will be thefirst part to touch the media in the event of head-to-media contact.

It will be understood that the terms “first and second heater currents”refer generally to an amount of current applied to at least one heaterthat maintains a desired close point location during first and secondoperational modes. The heater currents may be varied during operation toaccount for imperfections in the media, shock/vibration, etc. As such,it may be possible that instantaneous values of the current may be thesame in two different operational modes, if only momentarily. However,the average value of the currents over time will be different, resultingin the desired close point location.

In FIG. 5, a block diagram illustrates a system according to an exampleembodiment. The system includes a control block 504 coupled to amagnetic read/write head 502. The magnetic read/write head 502 includesa heater 506 used at least to control ABS protrusion of the read/writehead 502. The heater 506 may include a combination of components such asresistive heater, a write transducer, and a laser. The laser heats theABS via an energy path, e.g., waveguide and near-field transducer. Thewrite transducer may include a coil that generates heat when activated.In such a case, a resistive heater may be energized during reads (e.g.,activation of read transducer 510) to achieve a first ABS protrusion,and the write coil and/or laser may be energized during writes (e.g.,activation of write transducer 512) to achieve a second ABS protrusion.The heater may be activated or deactivated to achieve the secondprotrusion. Other combinations may be possible. For example, a secondheater may be used together with a first heater, write coil, and/orlaser, and may include more than two protrusion modes.

A thermal sensor 508 is placed near the ABS (media-facing surface) andprovides a signal used by clearance module 518 to control heater 506.More than one thermal sensor may be used. The thermal sensor 508 is usedby a clearance module 518 to control ABS protrusion, e.g., detectmedia-ABS clearance and media-ABS contact. The thermal sensor 508 may becentrally placed so that it does not move significantly relative to theABS in different modes, e.g., between time periods corresponding to thefirst and second protrusions.

While the first and second protrusions may be generally associated withread and write modes, other or additional operational modes may have adedicated protrusion profile. Such operational modes may includeseeking, self-test, reading servo wedges, etc. Generally, read and writemodes may include any time period during which the read/write head isreading/writing data to the recording medium. Such modes may alsoinclude time periods before and after the reading/writing, such as pre-and post-operations (e.g., warm up, stabilization, etc.).

The control block 504 also includes a processor 516. The processor 516may include logic circuitry operable alone or with software/firmware.The processor 516 may be part of a system-level device (e.g., system ona chip) having multiple, special duty circuit modules. The processor 516may include analog and digital circuits for, among other things,processing data read from the medium via a read channel 520 andprocessing data stored to the medium via the write channel 522 and(optionally) laser 514.

The clearance module 518 sends at least first and second energizingcurrents to the heater 506 resulting in first and second close pointsbetween the read/write head 502 and a recording medium. One of the firstand second energizing currents may be zero. For example, the currentsent to heater 506 may zero at least momentarily during writeoperations, in which case protrusion is provided by heat from the writetransducer 512 and/or the laser 514. The heater 506 may still beactivated during write operations to provide fine adjustment of theclearance.

In FIG. 6, a flowchart illustrates a method according to exampleembodiments. The method involves determining 600 a first operationalmode, which may be a read mode, write mode, or other operational modedescribed herein. If in the first mode, a first energizing current isapplied 602 to a heater of a magnetic head resulting in a first closepoint between the magnetic head and a recording medium. For example, ifthe first mode is a read mode, the first close point may correspond to(e.g., be proximate to) a read transducer.

A second mode may also be determined as indicated by block 604, in whichcase a second energizing current as applied 606 to the heater responsiveto entering the second operational mode of the magnetic head. The secondenergizing results in a second close point between the magnetic head andthe recording medium, the second close point at a different location onthe media-facing surface than the first close point. For example, if thesecond mode is a write mode, the second close point may correspond to(e.g., be proximate to) a write transducer or a contact pad between thewrite transducer and read transducer. The second close point in such acase may be influenced (e.g., a location and/or magnitude of the closepoint is affected by) by the write transducer and/or an energy deliverypath used in a HAMR-type device that is activated by a laser or similarenergy source.

In some embodiments, the first and second modes may be consideredmutually exclusive, e.g., the magnetic head is not in the first andsecond modes at the same time. This does not exclude the possibility ofother modes, in which case the magnetic head may be in neither the firstor second operational mode. In other cases, the first and second modesmay not be mutually exclusive. In such a case, a weighting factor may beapplied to the first and second energizing currents (or some otheradjustment performed) that can selectably move the close point over arange of locations.

It will be understood that the use of terms such as top/bottom,first/second, left/right, etc. are not intended to limit the describedfeatures to any implied relative importance, absolute orientation,relative order, etc. Unless otherwise stated, terms such as “first” and“second” are used for convenience of description and may be usedinterchangeably in the description.

The foregoing description of the example embodiments has been presentedfor the purposes of illustration and description. It is not intended tobe exhaustive or to limit the inventive concepts to the precise formdisclosed. Many modifications and variations are possible in light ofthe above teaching. Any or all features of the disclosed embodiments canbe applied individually or in any combination are not meant to belimiting, but purely illustrative. It is intended that the scope belimited not with this detailed description, but rather determined by theclaims appended hereto.

What is claimed is:
 1. A method comprising: applying a first energizingcurrent to a heater of a magnetic head responsive to entering a firstoperational mode of the magnetic head, the first energizing currentresulting in a first close point between a media-facing surface of themagnetic head and a recording medium, the first close point proximate toa read transducer of the magnetic head; and applying a different, secondenergizing current to the heater responsive to entering a secondoperational mode of the magnetic head, the second energizing currentresulting in a second close point between the media-facing surface andthe recording medium, the second close point proximate to a contact paddisposed at the media-facing surface between the read transducer and awrite transducer of the magnetic head.
 2. The method of claim 1, whereinthe first and second operational modes comprise respective read andwrite modes during which the respective read and write transducers ofthe magnetic head are used for reading and writing to the recordingmedium.
 3. The method of claim 2, further comprising energizing thewrite transducer during the write mode, wherein the energized writetransducer contributes to the heat deformation at the media-facingsurface and influences the respective first and second close points. 4.The method of claim 3, further comprising energizing a laser during thewrite mode, the energized laser contributing to the heat deformation atthe media-facing surface and influencing the first and second closepoints.
 5. The method of claim 2, further comprising energizing a laserduring the write mode, the energized laser contributing to the heatdeformation at the media-facing surface and influencing the first andsecond close points.
 6. The method of claim 1, further applying thirdand fourth energizing currents to a second heater during the respectivefirst and second operational modes, the first and third energizingcurrents resulting in the first close point, the second and fourthenergizing currents resulting in the second close point.
 7. The methodof claim 1, wherein the contact pad comprises a push block extendingwithin the magnetic head away from the media-facing surface, the pushblock formed of a first material with a relatively high coefficient ofthermal expansion relative to the read and write transducers.
 8. Themethod of claim 7, wherein the contact pad further comprises a hard,corrosion-resistant coating covering the push block at the media-facingsurface.
 9. The method of claim 1, further comprising measuring aclearance between the magnetic head and the recording medium via atemperature sensor, and wherein a location of the temperature sensorbetween the first and second close points minimizes changes in theclearance when the first and second energizing currents are appliedresulting in the first and second close points.
 10. A method comprising:applying a first energizing current to a heater of a magnetic headresponsive to entering a read mode, the first energizing currentresulting in a first close point between a read transducer of themagnetic head and a recording medium; and applying a different, secondenergizing current to the heater responsive to entering a write mode ofthe magnetic head, the second energizing current resulting in a secondclose point between a contact pad of the magnetic head and the recordingmedium, the contact pad disposed at a media-facing surface between theread transducer and a write transducer of the magnetic head.
 11. Themethod of claim 10, further comprising energizing the write transducerduring the write mode, wherein the energized write transducercontributes to the heat deformation at the media-facing surface andinfluences the respective first and second close points.
 12. The methodof claim 10, further comprising energizing a laser during the writemode, the energized laser contributing to the heat deformation at themedia-facing surface and influencing the first and second close points.13. The method of claim 10, further applying third and fourth energizingcurrents to a second heater during the respective first and secondoperational modes, the first and third energizing currents resulting inthe first close point, the second and fourth energizing currentsresulting in the second close point.
 14. The method of claim 10, whereinthe contact pad comprises a push block extending within the magnetichead away from the media-facing surface, the push block formed of afirst material with a relatively high coefficient of thermal expansionrelative to the read and write transducers.
 15. The method of claim 14,wherein the contact pad further comprises a hard, corrosion-resistantcoating covering the push block at the media-facing surface.
 16. Themethod of claim 10, further comprising measuring a clearance between themagnetic head and the recording medium via a temperature sensor, andwherein a location of the temperature sensor between the first andsecond close points minimizes changes in the clearance when the firstand second energizing currents are applied resulting in the first andsecond close points.
 17. A method comprising: applying first and secondenergizing currents to respective first and second heaters of a magnetichead responsive to entering a read mode, the first and second energizingcurrents resulting in a first close point between a read transducer ofthe magnetic head and a recording medium; and applying a different,third and fourth energizing currents to the respective first and secondheaters responsive to entering a write mode of the magnetic head, thethird and fourth energizing currents resulting in a second close pointbetween a contact pad of the magnetic head and the recording medium, thecontact pad disposed at a media-facing surface between the readtransducer and a write transducer of the magnetic head.
 18. The methodof claim 17, further comprising energizing one or both of the writetransducer and a laser during the write mode, the energized laser andenergized write transducer contributing to the heat deformation at themedia-facing surface and influencing the first and second close points.19. The method of claim 17, wherein the contact pad comprises: a pushblock extending within the magnetic head away from the media-facingsurface, the push block formed of a first material with a relativelyhigh coefficient of thermal expansion relative to the read and writetransducers; and a hard, corrosion-resistant coating covering the pushblock at the media-facing surface.
 20. The method of claim 17, furthercomprising measuring a clearance between the magnetic head and therecording medium via a temperature sensor, and wherein a location of thetemperature sensor between the first and second close points minimizeschanges in the clearance when the first and second energizing currentsare applied resulting in the first and second close points.